Answer to Question 1ANS: A
The oceanic crust is denser in comparison to continental crust. The oceanic crust is mainly composed
of basalt which is a heavy, dark colored rock. It contains oxygen, silicon, magnesium, and iron.
Information can be found in the section Earth's Inner Structure Was Gradually Revealed.
Answer to Question 2ANS: C
The argument as to the age of the Earth was already happening, but Charles Darwin and Alfred Russell
Wallace added to the debate with their theory of natural selection. Natural selection was a process that
required long periods of time to generate the diversity of life on Earth. Information can be found in the
section A New Understanding of Earth Evolved Slowly.